again on Ebay, snapshot in time, anyone can duplicate this and generally numbers will be about the same but the totals will always fluctuate
total world coins for sale: 314,228 graded total was 19,204 or 6.1%
NGC 13,491 71%
PCGS 4,401 23%
ANACS 792 4%
ICG 520 3%
Plenty of room for all to grow here as World coins that are graded are very few and far between. NGC has been grading World coins for many more years than PCGS.
Another area for growth is Ancient Coins (Greek, Roman, etc). PCGS does not grade those coins at all. The other 3 do.